Molded pallet

ABSTRACT

The invention relates to lightweight, nestable, reusable, molded plastic pallets used for support and transport of articles stacked thereon. The pallet has a generally corrugated structure, the transverse cross-sectional contour of the corrugations being trapezoidal in shape. The corrugations in the medial portion of the pallet are formed in concentric rectangles so as to reinforce each other and minimize distortion and racking. A series of spaced corrugations are also positioned in parallel relation to each side of the pallet. All corrugations are reinforced in a direction opposite to the longitudinal axis of the corrugations by integral spaced ribs between the corrugations at the top face and lower face of the platform. These reinforcing ribs are aligned so as to provide continuous spaced beams or extending through the pallet body lengthwise and crosswise to provide maximum strength and stiffness in the direction opposite to the axes of the corrugations. The construction results in omnidirectional strength and stiffness of the pallet. The ribs are also of such height as to act as stacking supports when the pallets are nested to provide strength to hold and distribute the weight of the stacked pallets and also to prevent jamming and sticking together of one pallet within another. The pallet is provided with a plurality of spaced integral hollow feet depending from the bottom face of the platform which have a rectangular truncated pyramidal contour. The inner bottom walls of the feet are provided with integral reinforcing cross-ribs. The side walls of the feet are also reinforced by the adjacent ends of the corrugations integrally molded therewith. The pallet is also provided at its outer periphery with a continuous integral L-shaped turned-down channel which is also reinforced with spaced transverse ribs to protect the edges of the pallet against abuse or damage by accidental mechanical impact.

United States Patent Wharton Nov. 7, 1972 1541 MOLDED PALLET Thomas P.Wharton, Neehah, Wis.

[73] Assignee: Menasha Corporation [22] Filed: April 5, 1971 [21] Appl.No.: 131,087

[72] Inventor:

Primary Examiner-Bobby R. Gay Assistant ExaminerGlenn O. FinchAtt0rneyJohn .l. Chrystal et al.

[5 7] ABSTRACT The invention relates to lightweight, nestable, reusable,molded plastic pallets used for support and transport of articlesstacked thereon. The pallet has a generally corrugated structure, thetransverse crosssectional contour of the corrugations being trapezoidalin shape. The corrugations in the medial portion of the pallet areformed in concentric rectangles so as to reinforce each other andminimize distortion and racking. A series of spaced corrugations arealso positioned in parallel relation to each side of the pallet. Allcorrugations are reinforced in a direction opposite to the longitudinalaxis of the corrugations by integral spaced ribs between thecorrugations at the top face and lower face of the platform. Thesereinforcing ribs are aligned so as to provide continuous spaced beams orextending through the pallet body lengthwise and crosswise to providemaximum strength and stiffness in the direction opposite to the axes ofthe corrugations. The construction results in omni-directional strengthand stiffness of the pallet. The ribs are also of such height as to actas stacking supports when the pallets are nested to provide strength tohold and distribute the weight of the stacked pallets and also toprevent jamming and sticking together of one pallet within another. Thepallet is provided with a plurality of spaced integral hollow feetdepending from the bottom face of the platform which have a rectangulartruncated pyramidal contour. The inner bottom walls of the feet areprovided with integral reinforcing cross-ribs. The side walls of thefeet are also reinforced by the adjacent ends of the corrugationsintegrally molded therewith. The pallet is also provided. at its outerperiphery with a continuous integral L-shaped turned-down channel whichis also reinforced with spaced transverse ribs to protect the edges ofthe pallet against abuse or damage by accidental mechanical impact.

10 Claims, 20 Drawing Figures PNENTEDunv 1 I972 SHEET 2 OF 7 FIG.2

3 I lc F'G 6 I. 0 ENTOR.

THOMAS F? WHARTON ATTORNEY.

FIG.3

THOMAS P WHARTON' ATTORNEY.

PATENTEDNW v 7 m2 sum 5 or 7 INVENTOR. OMAS P WHARTON ATTORNEY.

PATENTEDnuv 1 I972 3.702.100

sum 5 OF 7 INVENTOR. THOMAS P. WHARTON ATTORNEY.

PATENTED m 7 m2 SHEET 7 BF 7 INVENTOR. THOMAS P. WHARTON ATTORNEY.

MOLDED PALLET SUMMARY OF THE INVENTION This invention relates to arelatively lightweight, nestable, reusable pallet construction made ofmolded plastic material.

In the development of reusable molded plastic pallets, the majorobjective is to impart to the pallet the greatest stiffness and strengthwith the use of the least amount of material, least machine productiontime, and least investment in molding machinery. These requirements havebeen met by an invention which utilizes and combines a unique design, anefficient type of material, and a particularly suitable manufacturingprocess. 7

From the design standpoint, these requirements are met by the use of aunique corrugated platform. Since a corrugated platform is weaker, inbending strength and stiffness in the direction perpendicular to theaxes of the corrugations, however, three important structural featuresare embodied in the corrugated platform according to my invention toovercome this weakness. First, the corrugations are made generallytrapezoidal in shape, rather than in the conventional wavy corrugatedshape, to provide more material in the flange areas of thecross-section. These flat surfaces act as the flanges of an I-beam. Thenear-vertical portions of the corrugations act as the web of an I-beam,although they are sloped for easy removal from the mold and to permitnesting. This shape also provides the necessary flat surfaces on the topof the pallet platform for the pallet load and on the bottom of thepallet platform for sufficient area of contact with the tines of themechanical handling equipment such as lift trucks. Secondly, in themedial portion of the pallet the corrugations are positioned inconcentric rectangles so as to support each other and minimizedistortion and racking. This positioning of the corrugations alsoprovides greatest strength in the areas between the pallet feet whichwill bear on the tines of the lift truck when handled since thecorrugations run transverse to the lift truck tines. Thirdly, in thedirection opposite to the corrugations, which is the weaker direction ofany conventional corrugated structure, strength and stiffness areincreased by the provision of integral beams at ribs betweencorrugations on the top and bottom of the platform. These ribs arealigned so as to provide continuous spaced beams through the pallet bodyto provide maximum strength and stiffness in the direction opposite tothe corrugations.

From the standpoint of the type of material selected, greatest strengthand stiffnesscan be obtained with the least amount of plastic materialby the use of a type of plastic foam. With this material, the palletbody has walls of substantially uniform thickness and in crosssectionhave dense surface zones or skins and rigid interior cellular cores. Theoverall thickness, for example, may be /4 inch and the outer skin mayhave a thickness of 1/32 or l/l6 inch. A pallet of 40 X 48 inches insize would weigh only about 23 pounds. This type of material produces amolded pallet of unusual strength since the skins act as the flanges ofan l-beam and the interior cellular core acts as the web of the I- beam.

The stated goals can be achieved from a production standpoint by using aform of injection molding known as the structural foam process. Withthis process, the pallets are made by injecting into a closed moldhaving the required contoured elements, a plastic resin, such ashigh-impact polystyrene, high-density polyethylene, or otherthermoplastic containing a suitable foaming agent. The plastic foamcomposition is injected into the mold cavity which solidifies thecomposition in the areaimmediately adjacent to the mold surfaces butallows the composition to expand and then cool more slowly and form acellular structure in the core area. This results in pallet which has ahard solid smooth integral plastic skin and a cellular foam center orcore. The overall density of the resulting material is about half thatof solid plastic. In other words, the resulting structural foam is abouthalf air. The number of pounds of plastic resin needed to mold thepallet, therefore, is about half the amount which would be needed if thepallet were molded of solid plastic. Thus, a pallet can be made ofstructural foam for about half of the material cost.

The structural foam molding process employs low pressure molding andtherefore involves the use of less expensive molds, and this processalso permits the use of molding presses of lower capacity and lessinvestment cost. In addition, further efliciencies can be accomplishedby keeping all the structural members of the pallet construction of auniform and thin thickness, since the time cycle of the moldingoperation is determined by the time needed to cure the thickestcomponent of the pallet. Pallets can be molded in a relatively shorttime cycle, reducing molding costs. Automatic molding equipment isavailable so that labor costs are relatively low. All of these factorscontribute to the economic manufacture of this molded plastic pallet ofstructural foam plastic. I

Commercial methods of producing thermoplastic structural foams aredescribed in Modern Plastics Encyclopedia 1969-1970, published byMcGraw-I-Iill, New York, pages 243-247. Also in Foamed Plastics, Vol. 9,Encyclopedia of Chemical Technology, 2nd Ed. 1966, pages 847-884, andU.S. Pat. No. 3,268,636, Aug. 23, 1966.

ILLUSTRATIVE EMBODIMENT The advantages and novel features of my moldedpallet construction will be apparent from the following description ofthe preferred embodiment of my invention, wherein FIG. 1 is aperspective top view of the pallet,

FIG. 2 is a plan view of the top of the same pallet,

FIG. 3 is a plan view of the bottom of the pallet,

FIG. 4 is a side view of the pallet,

FIG. 5 is an end view of the pallet,

FIG. 6 is an end view of four nested and stacked pallets having theconstruction shown in FIG. 1,

FIG. 7 is a sectional view taken through a supporting leg of four nestedpallets along the line 7-7 shown in FIG. 2,

FIG. 8 is an enlarged sectional view taken through the deck of twonested pallets along line 8-8 of FIG. 2,

FIG. 9 is a sectional view taken through a supporting leg along line 9-9of FIG. 2,

FIG. 10 is a sectional view taken through the deck along line 10-10 ofFIG. 2,

along line 11-11 of FIG. 2, andalso illustrates the same view as takenon line lla-l 1a of FIG. 2,

FIG. 12 is a sectional viewtaken through a cross-rib along line 12-12 ofFIG. 2,

FIG. 13 is a sectional view taken through a support ing leg along line13-13 of FIG. 2,

FIG. 14 is a sectional view taken through the deck along line l4- 14 ofFIG. 2,

FIG. 15 is an enlarged sectional view taken through the deck on thecenter line of a row of cross-ribsalong line 15-15 ofFIG. 2,

FIG. 16 is a sectional view taken through a supporting leg along line16-16 of FIG. 2,

FIG. 17. is a fragmental exploded perspective view of a modified palletconstruction,

FIG. 18 is a perspective view of the bottom face of v face positioned tosupport any desired load thereon.

The pallet body is of a generally corrugated structure formed by aseries of spaced corrugations which extend in parallel relation to eachof the sides of the pallet. The

spaced corrugations extending in parallel relation to sides A and C ofthe pallet are designated by like numerals 2 to 13 inclusive in FIG. 2,and like numerals 15 to 24 inclusive designate the spaced corrugationsextending in parallel relation to sides B and D of the pallet. Thepallet construction is symmetrical with respect to its longitudinal axisA-A and transverse axis 8-8, shown in FIG. 1, so that each of the,quarter sections of the pallet has the same symmetrical contour andstructure.

Except for the channel 1 extending about the entire periphery of thepallet, the corrugations 2 to 13, and 15 to 24, have the same transversecross-sectional contour, as shown in FIGS. 8, 10, 11, and 14, which isin the form of a regulartrapezoid having inclined opposed sides andhorizontally disposed upper and lower connecting base portions, as shownfor example in FIG. 11. The horizontally disposed. base portions of thetrapezoidal corrugations constitute a top planar loading supportingplatform as shown in FIG. 1 and FIG. 2. Likewise, the opposed bottomplanar surface of the pallet is constituted by the horizontally disposedbase portions of the trapezoidal corrugations as shown in FIG. 3 andFIG. 20.

The inwardly positioned corrugations 7 to 1 3 inclusive and 18 to 24inclusive are arranged in a concentric rectangular pattern, as shown inFIGS. 1, 2 and 3, which are continuous for each of the respectiverectangles that constitute-the medial body portion of the pallet.

Each of the corrugations of the pallet is reinforced by spacedtransverse integrally molded reinforcing ribs designated by the letterR. These ribs are positioned in both the top and the bottom faces of thepallet body as shown in FIGS.'1, 2, .3, and 20. Each of these ribs Rextends to thesame height h from the base of each corrugation and isshorter than the height y within the sides of the corrugations, as shownin FIG. 8, as well as in FIGS. 1, 10, 11, and 14. These reinforcing ribsalso have substantially the same transverse crosssectional thickness, asshown for example in FIG. 12,

and are slightly tapered upwardly to permit easy removal of the partfrom the mold.

The reinforcing ribs R are longitudinally aligned and positioned atright angles with respect to each side of the pallet throughout thepallet construction as can be seen in FIGS. 1, 2,and 3. These ribs areintegrally molded with the respective inclined sides and connecting baseof the corrugations and function structurally as a series of reinforcingstruts constituting continuous uninterrupted beams, as shown in enlargedcross-section in FIG. 15. The ribs R merging with the adjacent sides ofthe corrugations reinforce the pallet body along, all its axes to resistbending stresses imposed on the load bearing upper deck as well-asagainst any upward lifting stresses imposed on the lower pallet surfaceby the tines of a fork-lift. An inspection of FIGS. 1, 2 and 3 clearlyshows that the described series of reinforcing ribs molded integrallywith the respective sides of the corrugations functions as spacedcontinuous reinforcing beams extending at right angles to each side ofthe pallet for the entire width and length of the pallet body.

As shown in FIG. 2, the intersecting corrugations 10 and 21 arereinforced at their corners by diagonal reinforcing ribs 21a. Alsointersecting corrugations 12 and 23 are reinforced at their corners bydiagonal reinforcing ribs 23a. Likewise as shown in FIG. 3, intersectingcorrugations 7 and 18 are reinforced at their corners by diagonalintegral reinforcing ribs l8a.,Also intersecting corrugations 9 and 20are reinforced at their comers by diagonal integral reinforcing ribs20a. Intersecting corrugations 11 and 22 are reinforced at their cornersby diagonal integral reinforcing ribs 22a. Intersecting corrugations l3and 24 are reinforced at their corners-by diagonal integral ribs 24a.These diagonally extending ribs are of the same height and thickness asreinforcing ribs R. It will be evident that. the described diagonallyaligned corner reinforcing ribs constitute continuous diagonal beamsreinforcing each of the corners of the rectangular corrugations whichresist stresses which may be imposed either on the deck or the bottomface of the pallet and minimize distortion and racking of the palletunder load stresses. The concentric rectangular corrugations provided inthe medial portion of the pallet reinforce each other.

The pallet. is also provided at its outer entire periphery with acontinuous integrally molded generally L-shap d. Channel,designated-generally by numeral 1 at the sides of the pallet. As shownin FIG. 10, charinel 1 is integrally molded with the side 2a of adjacentcorrugation 2. The side 1a of channel 1 extends downwardly to form aside margin of the pallet. Side 1a also slopes outwardly of the verticalat a slight angle to permit easy removal of the part from the mold, andhas a length which is somewhat shorter than the sides 2a of adjacentchannel 2 for a purpose to be explained later. The horizontal surface 10of channel 1 forms a relatively narrow flat margin which extends aboutthe entire periphery'of the pallet. The upper horizontal surface *1c isco-planar with the upper faces of the successive bases of channels 3,5,'etc. Channel 1 at side B of the pallet likewise has a similarcross-sectional contour and is integrally molded with the adjacent sideb of corrugation 15 as shown in FIG. 8. The respective channels arereinforced by spaced transverse ribs designated by numerals 1b. Theheight of ribs 1b is substantially the same as height of the reinforcingribs R" of the spaced corrugations previously described. As shown inFIG. 3, the spaced channel reinforcing ribs lb are aligned with thespaced reinforcing ribs R of the adjacent corrugations, therebyextending the strut reinforcement of the aligned ribs R to the marginalsides of the pallet as clearly shown in FIG. 15. The channels 1intersecting at each of the comers of the pallet are preferably roundedas shown in FIGS.

1, 2 and3, and are reinforced by reinforcing ribs 1d at each cornerwhere they intersect at right angles.

Referring to FIGS. 1, 2, 3, 4 and 5, the pallet is provided with aplurality of supporting feet, or legs, with these feet designatedgenerally by numerals 30, 32, 34 and 36, extending below the lower faceof the deck at each corner of the pallet, and with legs 31, 33, 35 and37 positioned intermediately of the corner legs. Also a still have thesame thickness and height as the other adjacent reinforcing ribs R withwhich they are aligned; otherwise, these ribs would either present anundercut which would catch on the mold or would have extra thicknesswhich would cause hot spots and imperfect mold and a longer coolingcycle.

FIG. 7 is a sectional view similar to FIG. 9 showing four identicalnested and stacked pallets. It will be seen that the supporting feet ofeach pallet, such as for example foot 37, nest within each other and theouter face of bottom wall c of each foot is supported and rests on theribs k, I and m projecting above the inner face of the adjacent bottomwall c" of the pallet feet. This construction ensures that the nestedfeet will not jam or bind together and will readily separate when theindividual pallets are separated. Also referring to r FIG. 8 whichillustrates two nested and stacked pallets,

supporting leg 38 is positioned in the medial portion of the palletbody. Each of the supporting legs has the shape of a truncatedrectangular pyramid having downwardly inclined opposed side walls a.opposed inclined end walls b, and bottom wall 0. The legs aresubstantially of the same overall dimensions and height, and have theirlonger sides a aligned lengthwise with the longer side B and D pallet asshown in FIGS. 2 and 3.

The bottom walls of the supporting feet are provided with a plurality ofopenings e which permitdrainage of the legs in event water accumulatestherein. Also these openings are adapted to receive fastening means forretaining auxiliary runners or a bottom platform as will be described inconnection with FIGS. 17 to 20 hereinafter. The bottom walls of thesupporting feet are reinforced with integrally molded ribs which extendfor a short distance above the bottom wall as shown in FIGS. 2, 7, 9 and16. The bottom walls of the comer supporting feet 30, 32, 34, and 36 andthe intermediate end supporting feet 33 and 37 are provided with spacedreinforcing ribs k and 1" which transversely inter- I sect medial rib mas shown in FIG. 2. The bottom walls of the intermediate supporting feet31 and and the medial supporting foot 38 are provided with integrallymolded reinforcing intersecting ribs 5 and t. As shown in FIG. 2, thesereinforcing ribs k, l, m, s and t are aligned with the respective ribsR" which reinforce the adjacent corrugations or with the near-verticalwalls of the adjacent corrugations.

Referring to FIGS. 1, 2 and 3, the ends of the corrugations 2 to 6 whichare parallel to the sides A and C of the pallet terminate and areintegral with the side walls a of the adjacent corner feet andintermediate supporting feet. Likewise, the corrugations 15, 16 and 17which are parallel to the sides B and D of the pallet terminate and areintegral with the end walls b" of the adjacent corner feet andintermediate supporting feet. As shown in FIG. 16, the reinforcing ribsR located at the upper open rib of the supporting feet are slightlyoffset from the adjacent side walls a as previously described, thetransverse reinforcing ribs R are of a height h less than the height yof the opposed inclined legs of the corrugations. This constructionprovides stacking supports for the entire platform of each pallet andalso prevents the stacked pallets from separately slipping and slidingsidewise.

Referring to FIGS. 6, 7 and 8, it will be seen that when the pallets arestacked, the marginal channel 1 is positioned so that the lower edge ofthe marginal leg 1a, abuts and is supported on the horizontal legportion 10 of the pallet nested beneath it. Also, the transversereinforcing channel ribs 1b also abut and are supported on thehorizontal legv portion 1c of the pallet therebeneath. It will thus beseen that all corresponding portions of the pallet are nestable and arecompletely supported by each other when stacked at any desired heightand can be individually removed from the stack without jamming orbinding together.

The advantages of usinglightweight thermoplastic structural foam inmaking the pallet construction were previously discussed. Referringagain to FIG. 15, the enlarged cross-section of the body portion of thepallet clearly illustrates the continuous solid plastic outer skin,designated by letter w, which is relatively thin compared to the innerrigid porous core, designated by letter x. As explained previously, suchstructural foam plastic has high structural strength and rigidity and isparticularly advantageous in providing pallets which overcome thedisadvantages or prior pallets.

MODIFIED PALLET CONSTRUCTIONS The previously described molded palletconstruction is adapted to be combined with auxiliary bottom platform 50which is suitably attached to the supporting feet of the pallet. Theauxiliary bottom platform 50 may be of a flat board or of corrugated orribbed configuration depending upon the desired strength and durabilityof the auxiliary bottom platform. Referring to so that they may bevertical, to facilitate molding, and

FIGS. 17 and 18, an auxiliary molded plastic platform 50 having the sameor slightly smaller overall dimensions as the molded pallet is attachedto the legs of the pallet by integrally molded fastening studs or pins53 that extend into the openings e in bottom surface of the supportingfeet of the pallet. The pins 53 are provided at their ends with flexibleor compressible frustro-conical shaped locking heads 54 made for exampleof a suitable elastomeric material which are shaped or adapted to bepushed or squeezed through the openings in the bottom walls of thesupporting feet of the pallet and then can expand inside the leg intolocking mechanical engagement with the inside face of the bottom wall ofthe legs, as shown in FIG. 19. The auxiliary bottom platform 50 may beprovided with a plurality of spaced openings 50a which are adapted toreceive or accommodate rollers or any elements protruding above thesupporting .base of a hand truck when the assembled pallet is' loaded onthe hand truck:

Instead of attaching a single auxiliary platform previouslyv described,separate spaced molded plastic bottom runner strips 51,52 and 53 may beattached to the aligned three rows of the supporting legs, as shown inFIG. .20, in a manner described above and shown in FIG. 19. The lengthof the runners may be the same or slightlyless than the lengthof thepallet. The runners vmay be aligned lengthwise or crosswise of thepallet.

The auxiliary bottom runners may be flat strips or of tural elements ofthe top and bottom deck surfaces of corrugated or ribbed configurationdepending upon the desired strength and durability of the auxiliarybottom runners.

ADVANTAGES OF THE INVENTION The molded plastic pallet also offers manyad-' vantages over conventional wooden pallets which are susceptible towean-warp, splitting, shrinkage, mildew, rotting, contamination andbreakage during reuse which entail prohibitive repair and maintenancecosts that are often greater than the replacement cost- My moldedpallet, in addition to being lightweight and easily handled, isunusually strong and resist fracture or other damage by accidentalimpacts. My pallet alsowill not wear, warp, shrink, mildew, rot ordeteriorate upon exposure to moisture and extremes of weather conditionsduring storage or use. They can be easily washed or sterilized. They canbe reused many times without repair costs.

Although, the present pallet is generally of a corrugated structure, itsunique design has remarkable omnidirectional strength and resistance tobending under load stresses through the full width and length of thepallet deck. The pattern of overall concentric enclosed rectangularcorrugations in the medial area of the pallet, as previously described,provides a deck with omnidirectional strengthsince it has no continuouslines of corrugations which would result in a weak axis, and has nointersections of corrugations, which would result in a point of stressconcentration. This strength and stiffness are increased by thetransverse aligned reinforcing ribs molded between the corrugations. inboth the top and bottom surfaces. of the deck which function as acontinuous beam. Furthermore, the reinforcing ribs are of suchpredetermined height as to act as stacking supports when the pallets arenexted to provide strength to hold the weight of the stacked pallets, aspreviously the pallet are proportioned so that the empty pallets can benested for shipment or storage. The pallets are molded of uniform wallthickness in matched metal molds which are the mirror image of the topand bottom surfaces of the pallet. The walls of the corrugations andfeet are sloped to facilitate release of the pallet from the mold. Theundersurfaces of the pallet have a taper that is the same as in theupper surface of the pallet so that the pallets are nestable. In mypreferred pallet construction, each pallet requires only about one inchof stacking height even though each pallet when supported on a floor isfive inches high. The top and bottom faces of the pallet are planar. Theloaded pallets can therefore be readily moved over a floor or may becarried on various conveying devices including those having a series ofrollers. The stacked nested pallets interlock with each other aspreviously explained, so that a stack of nested pallets willnot sliderelative to eachother and the stackwill not fall. v

The corrugated structure of the pallet provides .approximately equalexposed horizontal areas on the top and bottom surfaces of thepalletinasmuch as all the corrugations are of the same trapezoidalcross-section.

These horizontal surfaces also function as the flanges of an I-beam whensubjected to either downward or upward bending loads encountered bypallets. The hollow legs of the pallet which are molded in the form ofrectangular truncated pyramids have sloping sides at an angle whichpermit almost complete nesting. The reinforcing ribs in the bottom wallof the feet provide additional strength. The openings in the bottom wallpermit drainage of the hollow feet and also permit the attachment of asupplemental bottom deck or runners as previously described whichenhance the versatility of use of the present pallet construction. Alsoas explained previously the feet are reinforced at their sides by thespaced corrugations which terminate and are integrally molded withthesides of the legs. The parallel alignment of the legs permits thepallet to be rolled over roller-conveyors'without catching.

The construction of the pallet legs provides strength against buckling,breaking or overturning which is a common weakness in prior pallets. AsI previously described, the side walls of the legs which are integrallymolded and merged with the adjacent ends of the corrugations at the openend of the legs are reinforced and supported at the merged positions sothat stresses imposed on both the top andthe bottom surface of thepallet deck are more evenly distributed and thus the leg In addition tothe many structural advantages of the present pallet, as previouslyoutlined, the relatively low cost of the pallet offers considerablesavings in shipping or storage. Goods may be shipped loaded on thepallets directly to the consignee without removal of the pallets. Thisresults in saving of time required to unload the pallets before shippingand obviates reloading the goods on another pallet at the destination.The pallets may be stacked nested for storage or reshipment prior toreuse requiring very little storage space.

Other advantages of the molded plastic pallet besides its lightweightinclude low cubage, durability, capability of being pigmented for colorcoding, capability of being washed, resistance to mold, mildew, fungus,or rotting, and suitability for embossed markings for identificationpurposes. A rectangular pallet of size 40 by 48 inches having a uniformwall thickness of 34 inch made of molded structural plastic foam weightsapproximately 23 pounds as compared with conventional wooden palletswhich weigh from 70 to over 100 pounds each. Thus, empty pallets of thisinvention can be handled by laborers (male and female) as compared withwooden pallets which must be handled by lift trucks. One hundred palletscan be nested in a stack only 104 inches high, as compared with woodenpallets which require about five times this amount of space. This meansthat about five times as many empty plastic pallets can be shipped in atruck or rail car for about the same costs as the shipment of woodenpallets.

It is to be understood that the specific embodiments of the inventionherein described are illustrative of the novel features of thisinvention and that changes and modifications of the specific details ofconstruction may be made which are intended to be included within thescope of the appended claims.

I claim:

1. A unitary rectangular pallet for supporting and transporting loadsthereon comprising a body formed in a series of spaced parallelcorrugations, the transverse cross-sectional contour of the corrugationsbeing in the form of regular trapezoids having inclined opposed legs andhorizontally disposed upper and lower base portions interconnectingadjacent pairs of opposed legs, with each of said base portio having aninner face, the successive corrugations being reinforced by a pluralityof spaced beams integral with said inner faces of said base portions andat least a portion of each leg and extending transversely between pairsof said opposed legs and substantially perpendicularly from said innerface of the base portions, said beams being positioned in the successivecorrugations in longitudinal alignment constituting continuous beams forresisting bending stresses exerted on the pallet, the said horizontallydisposed exposed upper trapezoid base portions of said corrugationsconstituting a top planar load-supporting platfonn and the oppositelydisposed exposed lower portions constituting the bottom face of theplatform adapted for engagement by fork-lift tines or tying means forsecuring loads to the pallet.

10 2. A pallet as defined in claim 1 wherein the pallet is provided witha plurality of hollow supporting feet extending below the bottom face ofthe pallet platform and positioned in aligned spaced rows to permitinsertion of fork-lift tines therebetween.

3. A pallet as defined in claim 2 wherein the supporting feet andcorrugation are molded in a unitary struc-' ture, said feet beingnestable and tapered downwardly in a shape of a truncated rectangularpyramid having opposed inclined side walls and a bottom wall, theexternal bottom walls of said feet being flat and co-planar on theexposed exterior surface thereof and provided on the inner surfacethereof with integral reinforcing beams extending transversely betweenthe opposed side walls of the feet and extending for a relatively shortheight above said bottom wall. ,7

4. A pallet as defined in claim 3 wherein the bottom walls of. thesupporting feet are provided with openings adapted for drainage and forreceiving means to retain spaced auxiliary bottom runner strips or anauxiliary bottom platform.

5. A pallet construction as defined in claim 3 wherein spaced auxiliarybottom runner strips or an auxiliary bottom platform are attached to thebottom of the supporting feet. I t

6. A pallet as defined in claim 2 wherein a supporting foot ispositioned in the medial portion of the pallet and is concentricallyencompassed by a plurality of spaced corrugations, said corrugationsbeing in the form of concentric rectangles to provide omni-directionalstrength and stiffness.

7. A pallet as defined in claim 6 wherein the pallet is rectangular inshape and is provided with corner supporting feet near each comerthereof and intermediate ly positioned feet aligned with said cornerfeet and the medially positioned foot. y

8. A pallet as defined in claim 1 wherein the pallet is provided at itsentire periphery with a continuous L- shaped downturned channel, one legof said channel having the horizontally disposed exposed upper facethereof positioned in planar relation with the upper load-supportingsurface of the pallet, the other leg of said channel extendingdownwardly of the upper face of the pallet, and a plurality of spacedreinforcing beams integral with the inner faces of said channel legsextending transversely thereof and in alignment with the spaced beamsreinforcing the adjacent corrugations.

9. A pallet as defined in claim 6 wherein the pallet is provided with aseries of spaced corrugations of a longitudinal length less than theadjacent marginal sides of the pallet, said corrugations terminating atthe inclined walls of the supporting feet and being integrally moldedtherewith.

10. A pallet as defined in claim 1 wherein the pallet comprises a seriesof spaced corrugations positioned in parallel relation to each of themarginal sides of the pallet, the outermost corrugation at each sidebeing integral with an L-shaped downturned channel at each side of thepallet, the corrugations adjacent each of the sides of the palletterminating in integrally molded supporting comer feet positioned neareach corner of the pallet, additional supporting feet positioned at eachof the sides of the pallet intermediately of said corner feet, the sidewalls of said feet being integrally molded with 1 1 the adjacent ends ofsaid series of corrugations, the medial area of the pallet beingconstituted of a plurality of spaced corrugations molded in concentricrectangular pattern, and a supporting foot positioned mediallycorrugation, the innermost medially positioned positioned rectangularcorrugation being connected to the sides of the central leg by spacedreinforcing beams aligned with the spaced reinforcing beams of the adfthe pallet within the innermost rectangular shaped jacent corrugationsand the outer concentric rectangucorrugation, the L-shaped channel beingprovided with a series of spaced reinforcing transverse beams alignedwith the transverse reinforcing beams of the adjacent lar corrugationsbeing reinforced at the corners thereof by diagonal reinforcing beams.

I! I I I. I

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,702,1 Dated November 7, 1972 1nventor(S) Thomas P. Wharton It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

IN THE ABSTRACT Line 13, after "spaced" insert beams or-. Line 16, after"beams" cancel --or-.

' IN THE SPECIFICATION 1 I Column 1, line 46, cancel "at" and substituteo'r.

Column 5, line 65, cancel "rib" and substitue rim. Column 7, line 66,cancel "nexte'd" and substitute --nested-.

- IN THE CLAIMS Column 9, line 52, cancel "portio" and substitute-portions--. Column 12, line 1, cancel positioned-. (first occurrence)Signed and sealed this 29th day of Qctober 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. Y c. MARSHALL DANN Attesting Officer Commissioner ofPatents

1. A unitary rectangular pallet for supporting and transporting loadsthereon comprising a body formed in a series of spaced parallelcorrugations, the transverse cross-sectional contour of the corrugationsbeing in the form of regular trapezoids having inclined opposed legs andhorizontally disposed upper and lower base portions interconnectingadjacent pairs of opposed legs, with each of said base portio having aninner face, the successive corrugations being reinforced by a pluralityof spaced beams integral with said inner faces of said base portions andat least a portion of each leg and extending transversely between pairsof said opposed legs and substantially perpendicularly from said innerface of the base portions, said beams being positioned in the successivecorrugations in longitudinal alignment constituting continuous beams forresisting bending stresses exerted on the pallet, the said horizontallydisposed exposed upper trapezoid base portions of said corrugationsconstituting a top planar load-supporting platform and the oppositelydisposed exposed lower portions constituting the bottom face of theplatform adapted for engagement by fork-lift tines or tying means forsecuring loads to the pallet.
 2. A pallet as defined in claim 1 whereinthe pallet is provided with a plurality of hollow supporting feetextending below the bottom face of the pallet platform and positioned inaligned spaced rows to permit insertion of fork-lift tines therebetween.3. A pallet as defined in claim 2 wherein the supporting feet andcorrugation are molded in a unitary structure, said feet being nestableand tapered downwardly in a shape of a truncated rectangular pyramidhaving opposed inclined side walls and a bottom wall, the externalbottom walls of said feet being flat and co-planar on the exposedexterior surface thereof and provided on the inner surface thereof withintegral reinforcing beams extending transversely between the opposedside walls of the feet and extending for a relatively short height abovesaid bottom wall.
 4. A pallet as defined in claim 3 wherein the bottomwalls of the supporting feet are provided with openings adapted fordrainage and for receiving means to retain spaced auxiliary bottomrunner strips or an auxiliary bottom platform.
 5. A pallet constructionas defined in claim 3 wherein spaced auxiliary bottom runner strips oran auxiliary bottom platform are attached to the bottom of thesupporting feet.
 6. A pallet as defined in claim 2 wherein a supportingfoot is positioned in the medial portion of the pallet and isconcentrically encompassed by a plurality of spaced corrugations, saidcorrugations being in the form of concentric rectangles to provideomni-directional strength and stiffness.
 7. A pallet as defined in claim6 wherein the pallet is rectangular in shape and is provided with cornersupporting feet near each corner thereof and intermediately positionedfeet aligned with said corner feet and the medially positioned foot. 8.A pallet as defined in claim 1 wherein the pallet is provided at itsentire periphery with a continuous L-shaped downturned channel, one legof said channel having the horizontally disposed exposed upper facethereof positioned in planar relation with the upper load-supportingsurface of the pallet, the other leg of said channel extendingdownwardly of the upper face of the pallet, and a plurality of spacedreinforcing beams integral with the inner faces of said channel Legsextending transversely thereof and in alignment with the spaced beamsreinforcing the adjacent corrugations.
 9. A pallet as defined in claim 6wherein the pallet is provided with a series of spaced corrugations of alongitudinal length less than the adjacent marginal sides of the pallet,said corrugations terminating at the inclined walls of the supportingfeet and being integrally molded therewith.
 10. A pallet as defined inclaim 1 wherein the pallet comprises a series of spaced corrugationspositioned in parallel relation to each of the marginal sides of thepallet, the outermost corrugation at each side being integral with anL-shaped downturned channel at each side of the pallet, the corrugationsadjacent each of the sides of the pallet terminating in integrallymolded supporting corner feet positioned near each corner of the pallet,additional supporting feet positioned at each of the sides of the palletintermediately of said corner feet, the side walls of said feet beingintegrally molded with the adjacent ends of said series of corrugations,the medial area of the pallet being constituted of a plurality of spacedcorrugations molded in concentric rectangular pattern, and a supportingfoot positioned medially of the pallet within the innermost rectangularshaped corrugation, the L-shaped channel being provided with a series ofspaced reinforcing transverse beams aligned with the transversereinforcing beams of the adjacent corrugation, the innermost mediallypositioned positioned rectangular corrugation being connected to thesides of the central leg by spaced reinforcing beams aligned with thespaced reinforcing beams of the adjacent corrugations and the outerconcentric rectangular corrugations being reinforced at the cornersthereof by diagonal reinforcing beams.